KR100406594B1 - Pneumatic tires and manufacturing method - Google Patents

Abstract

The carcass has at least one circulating carcass cord fold, which is formed by at least one carcass cord zigzag extending in the circumferential direction of the tire and folded at both outer ends of the circulating carcass cord fold alternately to the left and right. It is. The bead core has an upper bead core portion formed by a helical winding on the circulating carcass cord ply with one or more stages in the circumferential direction of the tire and by the bead cord actually continuous to the carcass cord.

Description

Pneumatic tires and manufacturing method

(Background of invention)

The present invention relates to a pneumatic tire having improved bead durability and light weight, and a method of manufacturing the same.

(Field of invention)

In various pneumatic tires for commercial or heavy duty vehicles, both ends of the carcass are usually wound around the bead core and fixed. The winding height of the carcass is usually set higher than the rim flange height in order to securely hold the carcass against blow-up against internal expansion pressure or load weight.

However, when the pneumatic tire touches the ground, it is deformed as shown in FIG. 20, so that the portion 100 of the bead on the rim flange 104 tilts outwardly, so the bending and compressive stresses are carcass-folded. It acts repeatedly at the winding portion 102 of 101 and this stress is concentrated at the outer end of the winding portion 102. At the outer end of the winding portion 102, the carcass cord is interrupted in the cut section, so that the adhesion to the surrounding rubber is inferior, and with stress concentration, the looseness between the cord and the rubber is outside of the winding portion 102. Occurs early at the end. This starts the separation process of the carcass 101 and tends to cause bead damage. In particular, such bead damage tends to occur in radially structured tires in which the degree of deformation of the beads is increased due to the increase in the strength of the tire or tread for a large vehicle with a large deformation of the tire itself and a heavy load weight.

To prevent this damage, among other improvements, so far the amount of rubber in the bead upper rubber has increased to increase cushioning performance or to lengthen the time to reach looseness, or the cord reinforcement layer is inside the winding portion 102. And around and outside the bead core 103 to increase the strength of the bead 100 to reduce the amount of deformation itself.

However, this measure is insufficient to effectively prevent damage, especially in large load tires, and because the volume of beads increases further, the tire weight increases and fuel consumption is high.

As a result of the invention in light of this background, the inventors have been able to increase the bead durability in practice, using circular carcass cord plies with carcass cords arranged zigzag at both ends of the ply and fold in a U shape. It has been found that it can contribute to weight reduction by shaping the bead core by actually spirally winding the bead cord to the curse cord. In order to mold pneumatic tires of this structure, newer methods of manufacturing tires are also needed.

(Summary of invention)

It is a first object of the present invention to improve the adhesion of cords and rubber to both ends of the carcass ply, thereby reducing and dispersing the stresses acting on both ends of the ply, which actually increases bead durability and contributes to weight reduction. It is to provide a tire and a method of manufacturing the same.

It is a second object of the present invention to provide a pneumatic tire and a method for manufacturing the same, which can reinforce the strength of the bead core by employing a low modulus cord in the upper bead core portion and the carcass ply.

It is a third object of the present invention to provide a pneumatic tire having a carcass ply winding structure and a method of manufacturing the same, which can further improve the weight reduction of the tire and further improve the improved effect of bead durability. According to one aspect of the invention there is provided a pneumatic tire consisting of a carcass extending from a tread through a sidewall to a bead core in each of two bead portions and having at least one circulating carcass cord fold,

The circular carcass cord ply is provided with a plurality of folding points arranged in the circumferential direction of the tire at both outer ends of the circular carcass cord ply, and folds around each folding point of both outer ends alternately to the left and right. Formed by at least one carcass extending zigzag in the circumferential direction of the tire, and

The bead core has an upper bead core portion disposed radially outwardly of the circulating carcass cord ply at the bead portion and is an upper bead spirally wound to one or more stages in the circumferential direction of the tire and substantially continuous to the carcass cord. Molded by the core.

The circulating carcass cordfold preferably has a parallel cord arrangement in the fold main portion between the bead cores.

The bead core may be provided with a lower bead core spirally wound in the circumferential direction of the tire and formed by a lower bead core that is continuous or discontinuous on the carcass cord.

The outer end of the circulating carcass cord ply ends either inside the bead core or on the radially inner surface of the bead core or protrudes from the bead core in the tire axial direction to form a protrusion. The protrusions can be wound radially outward and terminate at the axial outer surface of the bead upper rubber or bead core. Or the protrusion extends between the bead core and the bead upper rubber and is wound radially outwardly and ends on the axial inner surface of the bead upper rubber or between the bead core and the bead upper rubber.

In the second invention, a method of manufacturing a pneumatic tire comprises: an inner liner mounting step of winding the inner liner rubber sheet cylindrically and annularly expandably around the outer circumference of the main tire forming machine;

A carcass fold forming step of forming a tubular fold base body for carcass by rotating the carcass cord circumferentially on the outer circumference of the inner liner rubber sheet while alternately folding from side to side on the main tire forming machine;

A bead forming step of forming a bead core while spirally winding the bead cord to the carcass cord in a small width to one or more stages on both sides of the ply base body;

Combining the tire forming members containing the bead upper rubber with each other on a fold base body provided with a bead core; And

An inflating step of inflating the main tire forming machine to obtain a tire main body; Consists of

In the carcass ply forming step, the carcass cords are preferably arranged in parallel in the ply main part extending between the bead cores.

The expansion step includes a sidewall forming step of joining the sidewall rubber by expansion of side molding machines provided on both sides of the main tire forming machine.

When the bead core has a lower bead core portion and an upper bead core portion, the lower bead core portion may be shaped by spirally winding the lower bead cord in a continuous or discontinuous manner to the carcass cord prior to the carcass fold forming step. .

The bead forming step molds the bead core so that the side ends of the fold base body are aligned with the outer surface in the axial direction of the bead core, or are kept aligned inward from the axial outer surface of the bead core, or protrude from the axial outer surface of the bead core. do.

1 shows a pneumatic tire 1 as a radial tire for a large vehicle in this embodiment, where the tire 1 is a tread 2, a sidewall 3 extending radially inward from both ends of the tread 2. And a conical tire base body 6 consisting of a bead portion 4 positioned at the inner end of both side walls 3 and reinforced by an annular bead core 5. The tire 1 also has a carcass 7 extending along the tire body 6 and a coarse belt layer 9 disposed radially outside the carcass 7.

The belt layer 9 consists of at least one belt ply, in which the first, second, third and fourth belt plies 9A to 9D are sequentially arranged on the carcass. The first belt ply 9A is provided with belt cords arranged at an angle of about 60 ° to 70 °, for example, on the dividing line C of the tire, and the second, third and fourth belt plies 9B to 9D. ) Has belt cords arranged at an angle of about 10 ° to 25 °. Incidentally, the direction of cord inclination with respect to the tire dividing line C between the second and third belt plies 9B and 9C is different, forming a truss structure, which increases the belt rigidity and by the strong edge effect Reinforce the tread (2).

The belt cord can be composed of steel, aromatic polyamide, aromatic polyester, high elastic polyethylene and other high modulus fiber cords, for example. Each belt cord is cut and cut at the outer end of the ply, for example the first belt ply 9A is about the same width as the third belt ply 9C and is more than the second belt ply 9B. Narrow, so the outer end position is different. The fourth belt ply 9D of the minimum width serves as a breaker for protecting the carcass 7 and the inner belt plies 9A to 9C. Both ends of the belt layer 9 gradually deviate from the carcass 7 and this space is filled with a relatively soft rubber cushion 42.

The carcass 7 is composed of at least one, and in this embodiment is one carcass ply 11 of the carcass cord 10 arranged at an angle of 75 ° to 90 ° with respect to the tire dividing line C. have. The carcass ply 11 passes through the conical main portion 11A between the bead cores 5 and the radially inner surface of the bead core 5 in this embodiment, thereby allowing the bead cores 5 from inside to outside in the axial direction of the tire. The winding part 11B which winds around is provided. The winding portion 11B extends along the axial outer surface of the bead end rubber 8 which extends radially outward from the bead core 5.

The winding height H1 from the bead base line BL is smaller than the bead tip height H2, which in this embodiment is smaller than the height HF of the rim flange F. Here, the bead base line BL is a reference line for selecting the rim diameter of the rim applicable to refer to a line in the tire axial direction passing through the axial outer end point of the bead base face 4S.

The carcass fold 11 is a circular carcass cord fold, wherein at least one carcass cord 10 extends zigzag in the circumferential direction of the tire and is folded at both ends of the fold 11 alternately from side to side, the main part 11A and the winding part 11B are shown in FIG.

In other words, the circulating carcass code ply 11 has several folding points Li, i = 1-n arranged at equal intervals in the circumferential direction at the outer end E1 of the ply 11 and the other external end E2. ) Have several folding points Ri (i = 1-n). The carcass cord 10 is alternately folded around the folding point at both outer ends E1, E2 in succession (Ri-1, Li-1, Ri, Li, Ri + 1, Li + 1). In this circulating carcass cord ply 11, the number of cords per 5 cm of the width of the ply is about 18/5 cm to 40/5 cm, and the carcass cord 10 does not intersect each other at least in the main part 11A and is actually parallel. Are arranged. If they intersect, shear forces occur, which can cause the cord to break.

On the other hand, since the fold outer ends E1 and E2 end at the bead portion 4 or the side wall 3 as shown in FIG. 3, the fold points Ri and Li are arranged at both sides of the tire 1. do.

The circular carcass cord ply 11 is formed using one or several carcass cords 10, an example of using two cords 10A and 10B is shown in FIG. At this time, the 2n point elements are arranged at each one of the outer ends E1 and E2 at equal intervals in the circumferential direction, and one folding point is composed of all the two point elements P. One carcass cord 10A extends zigzag in the circumferential direction and is folded at all two point elements P. FIG. The other carcass cord 10B is ½ pitch shifted in the circumferential direction compared to one carcass cord 10A, i.e., all of which are repeatedly folded at the two point elements P by one point element P. All. The carcass cords 10A, 10B are therefore arranged in parallel at least in the main part 11A.

5 shows a case where a cyclic carcass code ply is formed by using three carcass codes 10A, 10B, and 10C. In this case, the 3n point element P is arranged at each one of the outer ends E1 and E2 and the carcass codes 10A, 10B and 10C are all folded at the three point elements P and zigzag. The zigzag arrangement of each code is shifted by one third pitch, i.e., by one point element each. Therefore, three carcass codes 10A, 10B and 10C are arranged in parallel.

When forming the carcass ply 11 of two to m-sheets, the zig-zag arrangement of the carcass cord 10 is repeated m times in the circumferential direction.

Incidentally, when the tire is formed into a bias structure as shown in FIG. 6, the carcass cord 10 is, for example, an inclined cord which rises to the left of 35 ° to 60 ° to the equal line C of the tire. Arranged in a zigzag between the folding points Li, Ri at an angle to form an inner circulation carcass cord fold 11L, and secondly, continuously with the cord angle rising to the right of 35 ° to 60 ° ( meandering) and the outer circular carcass code ply (11U) is achieved.

The bead core 5 is equipped with at least the upper bead core portion 5A of the so-called single winding type. The upper bead core portion 5A is disposed radially outside the circulating carcass cord ply 11 at the bead portion 4 and is formed by spirally winding the upper bead core 14 to one or more stages in the circumferential direction. The continuous cord 15 that is actually continuous to the carcass cord 10 is employed as the upper bead cord 14. That is, as shown in FIG. 4, in the zigzag arrangement, the continuous cord 15 is continuously transferred to spirally wound from the end J1, so that the circulating carcass cord fold 11 and the upper bead core portion 5A ).

Here, by "actually continuous", the upper bead cord 14 and the carcass cord 10 are one continuous cord without interruption, or the upper bead cord 14 and the carcass cord 10 are bonded, The interruption is engaged by welding or the like so that it is continuously connected integrally. Spiral winding from zigzag in areas other than the transition zone J, if the upper bead cord 14 is interrupted due to lack of material, etc. in the process of spiral winding, or if the carcass cord 10 is interrupted in the middle of the zigzag arrangement However, the spiral winding or folding can be continued from the end interrupted by the new cord without gluing, and the new cord must be identical to the cord before it was interrupted. When integrally connected by gluing or welding, the upper bead cord 14 and the carcass cord 10 may differ in material, thickness or twisting structure if necessary.

In the present embodiment, the bead core 5 is formed of only the upper bead core portion 5A, and the bead core 5 or the upper bead core portion 5A is formed in addition to the flat hexagonal shape shown in FIG. As shown in Figs. (A) to 7 (F), various cross sections may be formed such as a quadrilateral, a rectangular tetragon, a trapezoid, a parallelepiped, another tetragon, a triangle, a hexagon, and a circle.

As the continuous cord 15, nylon, rayon, polyester, vinylon, aromatic polyamide, aromatic polyester, high elastic polyethylene, organic fiber cord, steel, and other metal fiber cords can be used.

In order to reinforce the fitting of the rim and the beads, and to suppress the rim deviation and to suppress the deformation of the bead base 4S or the resulting heat generation, it is desirable to form the cord initial tensile modulus (E) of 1500 kgf / mm 2 or more. Do.

Therefore, in this embodiment, since the carcass cord 10 is repeatedly folded in a U-shape alternately at the fold outer ends E1 and E2, as shown in Figs. 8 (A) and 8 (B), Similarly, the load compressing the U-shaped inner rubber G1 resists the tensile force TA acting on the carcass cord 10 by the internal expansion pressure or the like, and the compression force TB acting due to the bead deformation. The load that tensions the inner rubber G1 resists, reducing the stress between the folded end and the outer rubber G2. Moreover, in this U-shape, the stress itself is dispersed. In addition, the cut end of the cord having a weak point in strength due to the concentration of stress and the weak adhesive force is excluded from the beads 4 since the carcass cord 10 and the upper bead cord 14 are continuous.

As a result, the winding height H1 can be set smaller than the rim flange height HF while preventing the carcass 7 from lifting, and an improvement in bead durability and a significant reduction in weight are achieved. If the winding height H1 is higher than the rim flange height HF, the cord looseness of the outer ends E1 and E2 can be effectively suppressed while also eliminating the formation of the conventional cord reinforcement layer to improve bead durability and reduce weight. Can be similarly achieved.

In addition to the upper bead core portion 5A, as the bead core 5, a single winding type lower bead core portion 5B spirally wound the lower bead cord 16 at one or more stages in the circumferential direction. As shown in Fig. A), the inner side of the ply 11 may also be provided, and the cord strength and the cord stiffness may be improved, thereby improving the fitting with the rim. Between the upper and lower bead core portions 5A, 5B, the winding portion 11B can be supported and effectively prevents the lifting of the carcass 7. Lower bead cord 16 may be continuous to cord 15, but may be formed of discontinuous separation cords. For example, when a conventional steel cord is employed in the lower bead core portion 5B, even if a low modulus cord having an initial tensile modulus such as nylon and polyester of 1500 kgf / mm 2 or less is employed as the continuous cord 15, it is necessary. Rim fitting force is obtained.

As the bead core 4, instead of the lower bead core portion 5B, a so-called tape bead type, in which a rubber coated tape with a steel cord of for example 4 to 6 parallel cords is wound, can be used. This tape bead type core portion 5C may be provided between the radially inner surface of the upper bead core portion 5A and the circulating carcass cord ply 11.

As in this embodiment shown in FIGS. 2 and 9A, the winding portion 11B passes axially outward from the upper bead core portion 5A while passing through the radially inner surface of the upper bead core 5A. It has a protruding portion 17. The protrusion 17 is wound radially outward and terminates along the axial outer surface of the upper bead core portion 5A or the axial outer surface of the bead end rubber 8, or as shown in FIG. 9B. (17) is wound in the reverse direction, that is, the portion 17 protrudes axially inwardly from the upper bead core portion 5A and is wound radially outward, and the axial inner surface of the bead core portion 5A or the bead end rubber ( End with 8).

As the winding part 11B, it may alternatively end on the radially inner surface of the bead core 5, as shown in FIG. 9 (C). In this case, as shown by the dotted lines in the figure, the outer ends E1 and E2 include a slight protruding end from the side of the bead core 5 in the tire axial direction.

In another example of the winding portion 11B, when the bead core 5 is composed of the upper bead core portion 5A and the lower bead core portion 5B or the core portion 5C, the outside of the winding portion 11B The ends E1 and E2 end in the bead core 5. More specifically, as shown in FIG. 10A, the outer ends E1 and E2 of the winding portion 11B end on the radially inner surface of the upper bead core 5A and the lower bead core portion 5A and the lower portion. It is held between the bead core portion 5B or the core portion 5C. Or as shown in FIG. 10 (B), the upper bead core portion 5A is divided into a radially inner portion 5A1 and a radially outer portion 5A2, and is axially through the radially inner surface of the upper bead core portion 5A. The outwardly projecting portion 17 is wound radially outward and the outer ends E1, E2 are held between the inner and outer portions 5A1, 5A2 and end. Or one of the portions 5A1, 5A2 is formed by the core portion 5C and ends up held between the core portion 5C and the other portion 5A1 or 5A2.

As shown in FIG. 11 (A), in another embodiment of the winding portion 11B, the portion 17 protruding axially outward from the upper bead core portion 5A is wound radially outward and the outer end ( E1, E2 are held end between the upper bead core portion 5A and the bead end rubber 8, or as shown in FIG. 11 (B), the upper bead core portion 5A and the bead end rubber Passing between (8), they are held between the carcass main portion 11A and the bead end rubber 8 to finish.

Among the above structures of the winding portion 11B, being designed to be held to end the outer ends E1 and E2 can reliably prevent the lifting and the cord looseness of the outer ends E1 and E2.

The manufacturing method of such a pneumatic tire 1 will be described below.

The method of making a pneumatic tire consists of as shown in Figures 12-14:

An inner liner mounting step 21 for winding the inner liner rubber sheet 31 around the outer circumference of the main tire molding machine 30,

Carcass ply forming step 22 for forming the tubular ply base body 32 for the circulating carcass cord ply 11 on the outer circumference of the inner liner rubber sheet 31,

Bead forming step 23 for forming the bead cores 5, 5 on both sides of the fold base body 32 while spirally winding the continuous cord 15,

A joining step 24 for mutually joining the fold base body 32 and the tire forming member 33, and

It consists of an expansion step 25 for inflating the main tire former 30 to obtain a tire main body 6. Steps 21 to 25 are performed in this order in this embodiment.

In the main tire forming machine 30, a diameter-expandable disc-shaped flange 36 is provided with a bladder that expands in a round shape while expanding to internal pressure through the bead lock 35 to secure the bead core 5. It is arranged at both ends of the cylindrical drum 34. At the outer end of the flange 36, the projections 36A forming the point element P for folding the cord are arranged at equal intervals in the circumferential direction. On both sides of the main tire former 30, the side former 37 is arranged concentrically with an inflatable bladder.

Therefore, as shown in FIG. 12 (A), in the inner liner mounting step 21, the inner liner rubber sheet 31 is cylindrically wound on the outer circumference of the main tire former 30 between the flanges 36. All.

As shown in FIGS. 12A and 15, in the carcass fold forming step 22, a pair of bobbins 39A and 39B to separately hold the two continuous cords 15A and 15B. They are moved reciprocally between one end position Y1 and the other end position Y2 axially outward from the flange 36, passing parallel to and axially opposite the axial center 40. Each time the bobbins 39A and 39B change direction at the positions Y1 and Y2, the main tire forming machine 30 repeats the intermittent rotation at a patch interval of 2P. Therefore, the continuous cords 15A and 15B fold alternately continuously at both folding points Li and R1, while advancing the folding points Li and Ri in the circumferential direction to correspond to the rotation speed of the main tire former 30. The tubular fold base body 32 is formed of as many layers as possible.

At this time, the continuous cords 15A and 15B are formed parallel to each other without intersecting between the two flanges 36. In this embodiment, the bobbins 39A and 39B, which complete the formation of one layer or the required number of layers of the ply base body 32, stand by at positions Y1 and Y2. A thin insulating rubber sheet (not shown) ) Is glued to the outer circumference of the ply base body 32 and the continuous cords 15A and 15B are coated with an inner liner rubber sheet 31 and an insulated rubber sheet, to prevent clutter of the arrangement of the cords. It is preferable to coat the continuous cords 15A, 15B with rubber or adhesive in advance, but the outer or inner circumference of the inner liner rubber sheet 31 may be coated later after forming the fold base body 32.

As shown in Figs. 13A and 16, in the bead forming step 23, the bobbins 39A and 39B are oriented in the bead core forming position Y3, on the inner surface axially from the positions Y1 and Y2. Y4), and by the reciprocating motion of the bobbins 39A, 39B at the core width W and with the continuous rotation of the main tire forming machine 30, the continuous cords 15A, 15B are spiral wound in several stages, The bead core 5 is molded into the upper bead core portion 5A on both outer peripheries of the ply base body 32. Incidentally, the helical winding of the continuous cords 15A, 15B can start from inside or outside in the tire axial direction of the bead core 5.

When using one continuous cord 15, leaving one part of the length needed to mold the bead core 5, on the other side the circulating carcass cord ply 11 and the bead core 15 are formed continuously, One bead core 5 is formed using the remaining length portion. When using three to N consecutive cords 15 after forming the circulating carcass cord ply 11, one and the other bead core 5 are each formed by N / 2 cords. In odd cases, one cord ends near the array end position J, or the bead core 5 is formed by a combination of (N-1) / 2 pieces and (N + 1) / 2 pieces, respectively. . In view of the improvement of the molding machine structure and the control bead durability, it is preferable to use two continuous cords 15.

As shown in FIG. 13 (B), in the joining step, the tire forming member 33 such as the bead end rubber 8 and the rubber cushion 42 is connected to the fold base body 32 with the bead core 5. Are combined with each other. At this time, the side wall rubber 41 which is one of the tire shaping | molding members 33 is arrange | positioned at the side molding machine 37. As shown in FIG. When engaging, it is preferable to lightly press the fold base body 32 and the tire forming member 33 by a roller or the like.

As shown in FIG. 14, in the expansion step 25, the cylindrical tread ring 44 stacking the tread rubber 43 and the belt layer 9 is radially spaced outward from the fold base body 32. At the same time, the bladder 30A of the main tire forming machine 30 and the bladder 37A of the side forming machine 37 are each inflated.

At this time, as the bladder 30A expands, the fold base body 32, which is formed in a cylindrical shape between the bead cores 5 and 5 and expands, presses the tread ring 55 to form the tire main portion 6A. do.

The protrusion 17 of the ply base body 32 protruding axially outward from the outer end of the bead core 5 is wound with the sidewall rubber 41 as the bladder 37A expands and the tire main part 6A. Is attached to and forms the tire main body 6 in the bed structure shown in FIGS. 2 and 9A. Prior to the expansion step 25, the flange 36 contracts in diameter and is retracted inward in the radial direction from the cylindrical drum 34, causing the protrusion 17 to be released and pivoted.

In the bead forming step 23, without shaping the protrusion 17, the continuous cords 15A, 15B can be wound approximately aligned with the outer end of the fold base body 32. That is, the ply outer ends E1, E2 are aligned with the axial outer ends of the bead core 5 or are kept slightly inward or outward from the outer ends, so that the bead structure shown in FIG. The tire main body 6 may be molded.

Prior to the joining step 24, the bladder 37A of the side former 37 is expanded, the protrusion 17 pivots to the radially outer surface of the bead core 5, and the bead end rubber 8 is bonded, As shown in FIGS. 11A and 11B, the tire main body 6 is formed in the bead structure.

Alternatively, as shown in FIG. 17, the carcass fold forming step 22 may precede the lower bead core forming step 26 to rotate the lower bead cord 16 helically on an inner liner rubber sheet. And by this the lower bead core portion 5B can be freely molded. At this time, as the lower bead code 16, the same code that is continuous with the continuous code 15 or a separate code that is not continuous may be used. The lower bead core shaping step 26 may be replaced by a tape bead shaping step of shaping the tape type core portion 5C while overlapping the bands of the cord.

As shown in FIG. 18, in the bead forming step 23, the lower core portion 5A1 is formed by spirally winding the continuous cord 15 on the fold base body 32 in about half the stages. The protrusion 17 is wound on the lower core portion 5A1 by inflating the side molding machine 37, and the continuous cord 15 is wound in a spiral to form the upper core portion 5A2. As a result, the tire main body 6 is molded in the bead structure shown in FIG. 10 (B). Alternatively, one of the core portions 5A1 and 5A2 can be molded to the core portion 5C by performing the tape bead forming step during the bead forming step 23.

FIG. 19 shows the forming means of the bead structure shown in FIG. 9 (B). As shown in the figure, the inner liner rubber sheet 31 is molded between the bead locks 35, 35 and the bead core 5 is molded on the bead lock 35. The bead end rubber 8 extending on the inner liner rubber sheet 31 is disposed on the bead core 5 and in the carcass fold forming step 22 the fold base body 2 is molded. Therefore, in this embodiment, in the bead forming step 23, the bead core 5 is molded before the bead base body 32 at the inner surface of the fold base body 32. After the bead lock 35 and the flange 36 are reduced in diameter in the radial direction to the position Y where they stand on the inner surface, the protrusion 17 rotates inward from the outside in the rotation process 26. Later, by arranging the cushion rubber 42 and the other tire forming member 33, the joining step 24 for joining by the pressing and inflating step 25 is subsequently performed.

In the carcass fold forming step 22, the carcass fold 11 in the bias structure can be molded, as shown in FIG. 6, at which time the car instead of the tread ring 44 in the joining step 24. The breaker and tread rubber are engaged in the middle of the ply base body 32 as one of the tire building members 33 at a cord angle close to the curse ply. By inflation step 25, the breaker and tread rubber are inflated together with the ply base body 32 to form a tire main body 6 in the bias structure. On the other hand, to improve steering stability while increasing bead stiffness, a reinforcing layer made of organic fibers or metal fiber cords may be added to the beads 4.

EXAMPLE

According to the above manufacturing method, in the configuration shown in FIG. 1, the radial tire for heavy load was experimentally assembled to the specifications of Tables 1 and 2 with a tire size of 11R22.5. Test tires were tested and bead durability (bead damage), bead heat generation, bead base deformability and tire weight were compared.

The test conditions are as follows.

1) Bead Heat Generation

The test tires were mounted on a deep bottom rim of 15 °, measuring 22.5 × 8.25 and driven on drums with an internal expansion pressure of 8.00 kgf / cm 2, a load load of 9000 kg and a speed of 20 km / h. Bead surface temperature was measured at a driving distance of 1000 km and the average value was indicated in the index with a conventional tire of 100. Smaller values mean lower heat generation, which is excellent.

2) Bead durability (bead damaged)

After driving the drum 5000 km under the same conditions, the tire was dismantled and the presence or absence of loose plies was examined. In Tables 1 and 2,? Indicates the absence of loose plies,? Indicates looseness at the end of the wound portion of the carcass ply, and x indicates the occurrence of carcass separation.

3) Bead Base Deformability

As indicated by the dashed-dotted line in FIG. 2, the deformation height ha of the upward deformation of the toe t of the bead base of the tire after the drum was driven 5000 km under the same conditions was measured, and the tire before driving to 100 was measured. In the index. Large values mean small deformations, ie excellent.

4) tire weight

The weight of the test tire was expressed in the index with a conventional tire of 100. Smaller values mean lighter weight, which is excellent.

As shown in Tables 1 and 2, in the tire of an embodiment molded according to the manufacturing method of the present invention, if the bead core and carcass were made of low modulus cords such as nylon and polyester, Bead heat generation and bead deformability were inferior but bead durability (bead damage) was improved. In particular, bead heat generation and bead deformability when using an organic fiber cord having an initial tensile modulus of at least 1500 kgf / mm 2 was equivalent to or better than that of a conventional steel cord tire (initial tensile modulus of about 19000 kgf / mm 2).

1 is a cross-sectional view showing an embodiment of a pneumatic tire molded by the manufacturing method of the present invention,

2 is an enlarged partial cross-sectional view of the bead portion,

3 is a perspective view showing the arrangement of the cord of the carcass with the bead core,

4 is a schematic diagram showing an example of a zigzag arrangement of carcass codes;

5 is a schematic diagram showing another example of a zigzag arrangement of carcass codes;

6 is a schematic diagram showing another example of a zigzag arrangement of carcass codes;

7 (A) to 7 (E) are schematic cross-sectional views showing examples of cross-sectional shapes of the bead cores,

8 (A) and 8 (B) are schematic cross-sectional views for explaining the action of the carcass ply,

9 (A) to 9 (C) are schematic cross-sectional views showing examples of bead structures that can be molded by the present invention;

10 (A) and 10 (B) are schematic cross-sectional views showing another example of the bead structure that can be molded by the present invention,

11 (A) and 11 (B) are schematic cross-sectional views showing another example of the bead structure that can be molded by the present invention,

12 (A) and 12 (B) are schematic diagrams for explaining the inner liner mounting step and the carcass ply forming step,

13 (A) and 13 (B) are schematic diagrams for explaining the bead forming step and the joining step,

14 is a schematic diagram for explaining the expansion step;

Figure 15 is a schematic perspective view for explaining the carcass fold forming step,

16 is a schematic perspective view for explaining the step of forming a bead,

17 is a schematic cross-sectional view for explaining the step of forming the lower bead core portion,

18 is a schematic cross-sectional view for explaining an example of the winding step of both ends of the carcass fold,

19 is a schematic cross-sectional view for explaining another example of the winding step of both ends of the carcass fold,

20 is a schematic cross-sectional view for explaining the stress acting on the bead when the tire is deformed.

Claims (14)

A pneumatic tire consisting of a carcass with at least one circulating carcass cord fold extending from the tread through the sidewall to the bead core in each of the two bead portions, The circular carcass cord ply is provided with a plurality of folding points arranged in the circumferential direction of the tire at both outer ends of the circular carcass cord ply, and folded around each folding point of both outer ends alternately to the left and right. Formed by at least one carcass extending zigzag in the circumferential direction of the tire, and The bead core has an upper bead core portion disposed radially outwardly of the circulating carcass cord ply at the bead portion and is spirally wound in at least one stage in the circumferential direction of the tire and is substantially continuous to the carcass cord. A pneumatic tire, characterized in that formed by the core. 2. The pneumatic pneumatic pouch according to claim 1, wherein the circulating carcass cord ply has a parallel cord arrangement, wherein the carcass cords are arranged in real parallel arrangement without intersecting each other in the ply main portions spread between the bead cores. tire. The circulating carcass of claim 1, wherein the bead core is formed by a lower bead core that is spirally wound at one or more stages in the circumferential direction of the tire and is continuous or discontinuous to the carcass cord and at the bead portion. A pneumatic tire having a lower bead core portion disposed inside the cord ply radially. The pneumatic tire according to claim 1, wherein both outer ends of the circulating carcass cord ply end inside the bead core. 2. The pneumatic tire according to claim 1, wherein both outer ends of the circulating carcass cord ply end on the radially inner surface of the bead core. 2. The bead according to claim 1, wherein both outer ends of the circulating carcass cord ply project from the bead core in the tire axial direction to form protrusions, the protrusions being at the sides of the bead end rubber or bead core located radially outward of the bead core. Pneumatic tires, characterized in that they are finished and wound radially outward. 2. The method of claim 1 wherein both outer ends of the circulating carcass cord ply protrude from the bead core in the tire axial direction to form a protrusion, the protrusion ending on the side of the bead end rubber or between the bead end rubber and the bead core. And a pneumatic tire passing between the bead end rubber and the bead core located radially outward of the bead core and wound radially outward. A method of making a pneumatic tire with a carcass extending from the tread to the bead core at each of the two bead portions, An inner liner mounting step of winding the inner liner rubber sheet cylindrically and annularly expandably around the outer circumference of the main tire former; A carcass fold forming step of forming a tubular fold base body for a carcass fold by rotating the carcass cord circumferentially on the outer circumference of the inner liner rubber sheet while alternately folding from side to side on the main tire forming machine; A bead forming step of forming a bead core while spirally winding the bead cord to the carcass cord in a small width to one or more stages on both sides of the fold base body; Coupling step of coupling the tire molding member containing the bead end rubber to the fold base body provided with a bead core to each other; And An inflating step of inflating the main tire forming machine to obtain a tire main body; Pneumatic tire manufacturing method characterized in that consisting of. 10. The method of claim 8, wherein the carcass ply forming step is characterized in that the carcass cords are arranged substantially parallel to each other in the ply main portion extending between the bead cores. The pneumatic tire manufacturing method according to claim 8, wherein the expanding step includes a sidewall forming step of joining sidewall rubber by expansion of side molding machines provided on both sides of the main tire forming machine. 9. The bead core according to claim 8, wherein the bead core has a radially outwardly arranged upper bead core portion and a carcass ply radially inwardly disposed lower bead core portion, and the method of manufacture is said carcass fold. And a lower bead core forming step of forming a lower bead core part by spirally winding the lower bead cord in a continuous or discontinuous manner to the carcass cord with a smaller width in one or more stages before the forming step. . The method of claim 8, wherein the forming of the bead comprises forming a bead core so that both ends of the fold base body are aligned with the outer surface in the axial direction of the bead core. The method of claim 8, wherein the bead forming step forms a bead core so that both ends of the fold base body are kept inwardly aligned from the axial outer surface of the bead core. The method of claim 8, wherein the bead forming step forms a bead core so that both ends of the fold base body protrude from an axial outer surface of the bead core.